Oklahoma State University donor and famed oilman T. Boone Pickens has died.

The long-time Dallas resident had battled back from a series of strokes and further head injuries from a fall in 2017.

A family spokesperson says he died of natural causes.

Pickens was born in Holdenville, Oklahoma.

He was 91 years old at the time of his death.

Pickens was a graduate of Oklahoma State University and was famous for his monumental donations to his alma mater.